How consistent are stock EGO sensors?

[Thor Johnson]

I know that they are not terribly accurate for getting exact A/F
measurements, but I bought 4 sensors the same day, and installed
them on the four output ports (about 3" down from the engine.  A
typical line of readings are:

   0x90  0x92  0x80 0x92 (forgive the hex.... these are
arbitrary, 0x70 is "stoich")

Does this mean that Cyl #3 is getting more air than the others (&
therefore needs more fuel, or needs to have its intake reworked),
or is this pretty much expected from ordinary $20 "universal
oxygen sensors"?

TIA,
Thor Johnson
thormj at iname.com